1. Unsegmented Worms

2. Flatworms

3. Flatworms Belong to the phylum platyhelminthes. (Plat = flat)
There are three classes:
Turbellaria
Trematoda
Cestoda

4. Characteristics of Flatworms
They are acoelomates (they don’t have body cavities)
They have bilateral symmetry
Show cephalization
Respiration through skin
Single opening to digestive tract (pharynx)

5. Class Turbellaria Spade-shaped head and two eyespots
Eat protozoans for scavenge
Flame cells remove waste
Are hermaphrodites (have male and female reproductive parts)
Can reproduce by regeneration
Are free-living

8. Class Trematoda Are parasitic flukes
Have suckers on both ends of the body
Can live inside or outside of host

9. Class Trematoda Nervous and excretory systems like turbellarians
Hermaphrodites
Have complex life cycles

11. Fluke Life-Cycles
The long and complex life-cycle of the fluke can be made easier to
understand through the use of a nonsense mnemonic :
Every - Egg Mirror - Miracidium (free-living in water) Spotted - Sporocyst (in snail) Red - Redia (in snail) Certainly - Cercaria (free-living in water/snail) Met - Metacercaria (in 2nd intermediate host) Approval - Adult

12. Class Cestoda Parasitic Tapeworms Long, ribbon-like bodies
Absorbs nutrients from host
Hermaphrodites

13. Tapeworm Anatomy

17. Roundworms
Roundworms

18. Roundworms Belong to phylum Nematoda
Pseudocoelomates (fluid filled body cavity)
Slender bodies that taper on both ends
Have mouth and anus
Can be free-living or parasitic

19. Pinworms live in human intestines

20. Trichinosis- a disease from eating infected pork

21. Cysts in Contaminated Pork

22. Rotifers Known as rotifers or wheel animals
Transparent, free-swimming microscopic animal
Freshwater & marine
Have a ring of cilia around mouth that rotates like a wheel to bring in food
Feed on unicellular algae, bacteria, & protozoa

23. Rotifers
Have a muscular organ called the mastax behind the pharynx to chop food
Nervous system composed of anterior ganglia & 2 long nerve cords
Show cephalization (head end)
Have 2 anterior, light-sensitive eyespots

24. Rotifer Anatomy